Valves have become more and more relevant to people’s daily lives as their uses have expanded. Examples include faucets for water mains, and pressure reducing valves for liquefied petroleum gas. Valves are also essential components in a variety of mechanical equipment such as internal combustion engines, steam engines, compressors, pumps, pneumatic actuators, hydraulic drive system vehicles, ships and aircraft.
In recent years, valve accidents occur frequently, and the safety of gas valves and pipeline valves has gradually been paid attention to by people. For example, most of the media in petrochemical production units are highly toxic, flammable, explosive and corrosive The operating conditions are complicated and harsh, the operating temperature and pressure are high, the operating cycle is long, once the valve fails, the light causes the medium to leak, I. E. Pollutes the environment and causes economic loss, the heavy cause the plant to stop production, even causes the malignant accident.
According to the statistics of refinery plant engineering, pipeline engineering accounts for about 10% ~ 30% of the total project, while the cost of valves accounts for 30% of the total project, which is the main component of pipeline engineering equipment Whether the valve can be used correctly not only relates to the safe operation of the project, but also has a greater impact on the economy of the installation project.
Petrochemical pipeline valves are usually selected gate valve, globe valve, check valve, safety valve, and ball valve, butterfly valve and other general valves, but also used a few special valves and special valves. Among them, the largest use of gate valves, accounting for about 80% of the total, globe valves accounted for 10%, the rest for the ball valve, butterfly valve, safety valve and check valve.
Material selection, mainly to carbon steel, accounting for 90%, the rest for alloy steel and stainless steel. In addition, general purpose valves are also widely used in storage and transportation systems, water supply and drainage systems, boiler systems, and self-contained power stations. It is necessary to explain that there are some differences in product selection and process use, and the data will be changed. But the approximate proportion relation will not have too big difference, some craft size difference is big, will need to the custom valve.
Valve standard that is to standardize the valve design, manufacture, inspection, use and other requirements, so that the manufacture and use of both sides have a common language, from the perspective of technical regulations to protect their interests, so that the evaluation of a unified standard. But in the past, some small enterprises did not put the quality problem in the first place, the valve body length is different, the valve material is not up to standard, the sealing material is poor, etc.
There Are 2 Major Problems With The Current Valve Quality:
(1) Defects In Valve Casting
Valve body material carbon steel, especially chrome-molybdenum steel valve body in the casting process prone to trachoma, Burr and micro-cracks, rough appearance. Friends who sell outside know that when customers check and accept, even a small trachoma burr will cause customers to fail the check and acceptance, and a large number of valves will have to be returned. Many sales do not understand, what does such a small trachoma and small burr have to do with it It doesn’t hurt to use it, but it’s kind of ugly. But experience with the unit tells them that quality is not just about the valve, but the attitude.
(2) Tightness Of The Valve
The tightness of the valve is an important index to measure the function and quality of the valve. The inner leakage of valve is a serious problem, which threatens the normal operation of the whole engineering equipment. Most of the internal leakage of valve units are used because the sealing surface material of valve plate and valve seat does not meet the use requirements, the processing accuracy is not enough, the wedge angle of gate valve plate and valve seat does not match, the sealing surface width varies, poor fit, gate plate is not in place, factors such as immobilization. There are packing assembly does not meet the requirements, resulting in leakage.
In recent years, with the development of petroleum, chemical industry, smelting and other industries, all kinds of harsh working conditions make the design and innovation of valve enterprises to meet all kinds of high pressure, high temperature and strong corrosive working conditions wear-resistant, hydrogen-resistant, sulfur-resistant demand is further enhanced. This also indicates the future direction of technological innovation in the valve industry.
Post time: Jul-28-2021